Anti-wear device for composite packers and plugs

ABSTRACT

A downhole packer tool having components made essentially of non-metallic engineering grade plastic materials. The tool having an apparatus for anchoring the tool in an annular structure. The tool has a mandrel; a slip assembly positioned on the mandrel, the slip assembly having at least one spacer ring and a plurality of slip elements; and at least one wear resistant insert installed in an outer surface of the tool and extending outwardly therefrom whereby the at least insert button is abrasion resistant upon setting yet has favorable drillability characteristics upon drilling the tool from the wellbore.

CROSS REFERENCE TO RELATED APPLICATIONS

None.

BACKGROUND

1. Technical Field

This application relates generally to downhole tools for use in oil andgas wellbores, and more particularly, to such tools having one or moredrillable components made from non-metallic materials, such asengineering grade plastics and composite materials. This applicationrelates particularly to downhole packers and plugs.

2. Background Art

In the drilling or reworking of oil wells, a great variety of downholetools are used to block or channel flow in the wellbore. For example,but not by way of limitation, it is often desirable to close off thewell or to seal the annulus around tubing or other pipe in the wellborecasing. Downhole tools referred to as packers tools are designed forthese general purposes and are well known in the art of producing oiland gas. As used herein the term, “packer tool” refers to a tool thathas an expandable seal or packing element that radially expands tocontact and seal against the wellbore tubing. Packer tools include, forexample: tools know as packers, bridge plugs and frac plugs.

Halliburton Energy Services, Inc. introduced to the industry a line ofdrillable packer tools currently marketed by Halliburton under thetrademarks FAS DRILL® and Obsidian®. These tools comprise componentsmade of non-metallic materials, such as, engineering grade plastics toimprove the drillability of such downhole tools. The FAS DRILL® andObsidian® line of tools has been very successful and a number of U.S.patents have been issued to Halliburton Energy Services, Inc., includingU.S. Pat. No. 5,271,468 to Streich et al., U.S. Pat. No. 5,224,540 toStreich et al., U.S. Pat. No. 5,390,737 to Jacobi et al., U.S. Pat. No.5,540,279 to Branch et al., U.S. Pat. No. 5,701,959 to Hushbeck et al.,U.S. Pat. No. 5,839,515 to Yuan et al., U.S. Pat. No. 5,984,007 to Yuanet al. and U.S. Pat. No. 6,394,180 to Berscheidt et al. The precedingpatents are specifically incorporated herein by reference.

The FAS DRILL® and Obsidian® type packer tools comprise a mandrel withelements mounted thereon for sealing against the wellbore wall and forcontacting the wellbore wall to anchor the tool in position in the well.The term “mandrel” is a term of art and comprises the structuralbackbone of the tool and is typically in the shape of a rod or tubewhich may or may not have a cylindrical exterior surface. In a processcalled setting, the sealing and anchoring element of these packer toolschange shape, in that, these elements radially expand into contact withthe wellbore wall. When these packer tools are lowered or run into thewell the packing and anchoring elements are in a run state (radiallycontracted to clear the wellbore wall) and the tools have been set inposition in the well these elements are in a set state (radiallyexpanded into contact with the wellbore).

Packing assemblies provide the sealing function and slip assembliesprovide the anchoring function. As used herein the term “packingassembly” means an assembly comprising one or more annular rings ofcompressible material which when axially compressed expands radiallyfrom the run state into contact with the wellbore wall. Packingassemblies may or may not include one or more back up and anti-extrusionrings. As used herein the term “slip assembly” means an assemblycomprising one or more wedges and slips which when axially compressedinteract to radially expand from the run state where the slips are incontact with the wellbore wall.

These packer tools also comprise elements for axially retaining thepacking and anchoring assemblies on the mandrel. These retainingelements comprise shoulders connected to the mandrel and located on themandrel adjacent the ends of the mandrel with the packing and anchoringassemblies confined there between. Typically, the shoulders are formedon annular shaped elements connected to or integrally formed on themandrel. The lower retaining element on the mandrel is sometimesreferred to as a “bullnose or muleshoe.” In the FAS DRILL® and Obsidian®type packer tools the muleshoe comprises an annular member of easilydrillable non-metallic material and has a larger outer diameter than thepacking and anchoring elements when in the run state. The upperretaining element in the In the FAS DRILL® and Obsidian® type packertools comprise a setting ring made of easily drillable non-metallicmaterial and has a larger outer diameter greater than the packing andanchoring elements when in the run state. This tool configuration withthe radially recessed packing and anchoring elements holds theseelements away from the wellbore wall and protects the packing andanchoring elements from damage and prevents the wellbore wall contactfrom causing premature element setting.

In some prior art packer tools ceramic teeth have been included in theslip elements to penetrate the wellbore wall for the purpose ofimproving the anchoring function. Ceramic teeth in slip segments aredescribed in detail in U.S. Pat. Nos. 5,984,007 and 6,394,180, which areincorporated herein by reference for all purposes. In other prior artpacker tools the slips are made of drillable cast iron with integrallyformed teeth. However, teeth on the slips cannot and do not contact thewellbore wall during run in of the tool and if they did they wouldfunction to penetrate the wellbore wall and interfere with the movementof the tool in the well.

It should be appreciated that while the tool is being run into the wellthat the non-metallic retaining elements contact the wellbore wall andhold the packing and anchoring elements out of contact with thewellbore. In today's hydrocarbon well environment, a large portion ofthese engineering grade plastics packer tools are run long distancesinto horizontally extending wells. As these tools travel in thesehorizontal sections, they are typically forced to one side and rideagainst the wellbore casing wall. This contact causes increased wear onthe engineering grade plastics parts of this tool. This wear or abrasioncan compromise the design and functionality of the tool.

Accordingly there is a need to provide protection of the tool againstwear or erosion damage caused by contact with the wellbore wall.

SUMMARY OF THE INVENTIONS

The present invention provides an improved packer tool with plasticcomponents which are protected to minimize damage from contact with thewellbore wall during installation in the well. The invention providessurfaces on the engineering grade plastic tool components that resistwear. According to a feature of the present invention, abrasionresistant materials are embedded in components of the downhole tool,such as, components with the largest outer diameters, to minimize thedamage to the components. In a preferred embodiment, wear resistantinserts are installed in the retaining elements, such as, the settingring and/or muleshoe of the downhole tool. In a preferred embodiment,the wear resistant inserts extend radially outward as far as or furtherthan the other components of the packer tool.

The inserts may be formed in whole or part of materials, such as,zirconia ceramic, metallic-ceramic composites or drillable cast ironmaterials whereby the inserts have a relatively high abrasion resistanceyet have favorable drillability characteristics upon drilling thedownhole tool from a wellbore.

Additional objects and advantages of the invention will become apparentas the following detailed description of the preferred embodiment isread in conjunction with the drawings which illustrate the preferredembodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings are incorporated into and form a part of the specificationto illustrate at least one embodiment and example of the presentinventions. Together with the written description, the drawings serve toillustrate and explain the principles of the invention. The drawingfigures are only for the purpose of illustrating at least one preferredexample of at least one embodiment of the invention and are not to beconstrued as limiting the invention to only the illustrated anddescribed example or examples. The various inherent advantages andfeatures of the various embodiments of the present invention areapparent from a consideration of the drawings in which:

FIG. 1 is an exemplary packer tool having anti-wear inserts embodyingthe present invention;

FIG. 2 is a plan view of an exemplary packer tool attached to a settingapparatus embodying the present invention,

FIG. 3 is a side elevation view of a muleshoe with and alternativeembodiment of an insert installed therein and embodying the presentinvention, and

FIG. 4 is a side elevation view of a muleshoe with an even furtherembodiment of inserts installed therein and embodying the presentinvention.

DETAILED DESCRIPTION

In the description that follows, like parts are marked throughout thespecification and drawings with the same reference numerals,respectively. The drawings are not necessarily to scale and theproportions of certain parts have been exaggerated to better illustratedetails and features of the invention. In the following description, theterms “upper,” “upward,” “lower,” “below,” “downhole” and the like asused herein shall mean in relation to the bottom or furthest extent ofthe surrounding wellbore even though the well or portions of it may bedeviated or horizontal. The terms “inwardly” and “outwardly” aredirections toward and away from, respectively, the geometric center of areferenced object. Where components of relatively well known designs areemployed, their structure and operation will not be described in detail.

Referring now to FIGS. 1 and 2, representative downhole packer toolillustrated in the run state. The tool 2 has a hollow mandrel 4extending through the tool. The particular packer tool 2 configurationillustrated FIG. 1 is referred to as a bridge plug and is characterizedby a plug 6 permanently mounted within mandrel 4 by radially orientedpins 8. Plug 6 has a seal means 10 located between plug 6 and theinternal diameter of mandrel 4 to prevent fluid flow therebetween.Without plug 6, the packer tool would be in the form of a packer.

Packer tool 2 includes a non-metallic spacer or setting ring 12 which ispreferably initially held in place on the mandrel 4 in the run state byshear pins. Ring 12 provides an abutment which serves to axially retainthe upper anchoring assembly comprising slip segments 18 and slip wedge20. Slip segments 18 and wedge 20 are positioned circumferentially aboutmandrel 4. Slip wedge 20 has a ring shape and axially slides on themandrel. Wedge 20 is initially positioned partially underneath slipsegments 18. In the FIG. 1 embodiment spacer ring 12 includes aplurality of wear resistant inserts 19 spaced around the periphery.According to the preset insertion, the wear inserts 19 extend radiallyoutward at least as far as or a further distance than the othercomponents of the tool 2.

Located below slip wedge 20 is at least one packing assembly, and asillustrated, the packing assembly comprises at least one packing element28. In some packer tools a packer shoe 29, also called an extensionlimiter, is included to provide axial support to respective ends ofpacking assembly 28. The particular packing assembly arrangement shownin FIG. 1 is merely representative as there are several packer assemblyarrangements known and used within the art.

Located below the packing assembly 28 is a lower anchoring assemblycomprising a slip wedge 20 and a plurality of slip segments 18. Itshould be noted that in some packer tools only one of the anchoringassemblies are present.

At the lowermost terminating portion of tool 2 is an angled portionreferred to as a muleshoe 30 mounted on the mandrel 4. In the FIGS. 1and 2 embodiments, a plurality of wear resistant inserts 19 in the shapeof buttons are mounted in the exterior of the muleshoe. These wearinserts are spaced around the periphery and extend radially outward adistance equal to or greater than the other components of the tool 2.The presence of inserts is especially important when the tool 2 is to beinstalled in a long lateral well.

The ring 12 and the muleshoe 30 (sometimes referred to as a bullnose)are made from material with improved drill out characteristics, forexample non-metallic engineering grade plastics. These two componentscomprise the retaining elements of the packer tool. The retainingelements bracket the packing and anchoring assemblies. In thisembodiment ring 12 and muleshoe 30 have a larger outer diameter than thepacking and anchoring assemblies.

In embodiments were wear inserts 19 in the form of buttons are installedto extend radially outward from the exterior surface of the ring 12 andmuleshoe 30. These inserts are positioned to contact the interior ofcasing 40 to prevent wear or degrading of the ring and muleshoecomponents of the tool 2.

Wear inserts 19 may be mounted in cavities (not shown) in the packertool by being molded into, or otherwise secured therein. The use ofadhesives to secure inserts 19 is recommended but other methods tosecure the inserts may be used.

Suitable materials for making inserts 19 may include abrasion resistantmaterials such as Zirconia ceramic, the materials described U.S. Pat.No. 5,984,007, drillable cast iron or other abrasion resistantmaterials. Inserts 19 may range from 0.250 (6.3 mm) to 0.375 inches (9.5mm) in diameter and from 0.250 inches (6.3 mm) to 0.500 inches (12.5 mm)in length depending on the nominal diameter and working pressures andtemperatures of the tool in which the insert inserts are to be used.

The subject inserts have a relatively high abrasion resistance whilestill maintaining the favorable characteristic of being drillable ormillable in a short period of time upon destructively removing thesubject tool from a wellbore. Further, due to the lesser density of theinserts taught herein, the present inserts are more easily circulatedaway from the drilling or milling bit by the fluid in the wellbore,thereby greatly improving drilling or milling speeds. This buttondensity if especially important when drilling or when lighter densityfluids are present in the wellbore, or annular structure, including butnot limited to, weighted or unweighted water and nitrogen/water mixture.

In the packer tool 3 embodiment of FIG. 2, the tool is illustratedattached to a setting tool S. In this embodiment wear inserts 19 areinstalled in the lower retaining element muleshoe 30 but are absent fromthe ring 12. In embodiments where, as illustrated, the outer sleeve S ofthe setting tool has an outer diameter of about equal to or greater thanthe ring 12. In this regard the sleeve S acts as the wear protection forthe upper end of the packer tool by suspending the upper end away fromthe wellbore wall. Indeed on some packer tools the ring 12 is eliminatedfrom the assembly by using the setting tool sleeve S to contact andexpand the anchoring and packing assemblies on the upper end of themandrel.

In the illustrated embodiments the wear resistant inserts 19 areillustrated as having cylinder shapes. However, other shapes andconfigurations of the inserts 19 are contemplated. It is anticipatedthat the inserts could be formed in other shapes, with quadrilateral,polygonal, and curved sided cross-sectional shapes.

In another embodiment, a ring shaped wear resistant insert is installedin at least one of the retaining elements. The ring shaped insert couldbe one or more continuous rings 19 a of wear resistant material moldedinto the outer surface of the retaining element as illustrated in FIG.3. The ring 19 a could be flush with or extend outward from the outersurface of the retaining element 30.

In an alternative embodiment, the inserts could comprise ring segmentsinstalled in one or more annular grooves formed in the outer surface ofthe retaining elements. These inserts could be mounted to extendradially outward at least a distance flush with the largest component ofthe tool.

In a further embodiment, the inserts could comprise plates attached toor imbedded in the outer surface of the retaining member. These insertsin the form of plates. The inserts 19 b could be narrow in width andextend axially along the outer surface of the retaining member to act asa skid as illustrated in FIG. 4. The outer surface of the insert 19 bextends radially outward at least as far as the muleshoe 30 and thelargest component of the tool.

The operation of packer tools is as follows. Tool 2 and 3 are loweredinto the wellbore 40 attached to a wireline setting tool of a type knownin the art. As the tool 2 is lowered into the wellbore 40, inserts 19act as a guides (especially in long horizontal wellbores) to protectfragile parts of the tool, such as parts made from engineering gradeplastics materials, from undesirable excessive contact with the wellbore40 or degrading due to excessive abrasion/erosion of the components. Inthe illustrated embodiments shown, the plurality of inserts 19 areinstalled in a preselected pattern in muleshoe 30 and spacer ring 12 oftools 2 and 3 to extend outwardly therefrom.

Once in position the packer tool is set in the wellbore and welltreatment operations are conducted. When it is desirable to remove thetool from the wellbore drilling or milling operations are used to breakthe packer tool up into pieces that are circulated out of the well. Aspreviously pointed out wear inserts made of ceramic material areadvantageous for this application.

Although the invention has been described with reference to a specificembodiment, the foregoing description is not intended to be construed ina limiting sense. Various modifications as well as alternativeapplications will be suggested to persons skilled in the art by theforegoing specification and illustrations. It is therefore contemplatedthat the appended claims will cover any such modifications, applicationsor embodiments as followed in the true scope of this invention.

1. A packer tool comprising: a mandrel; a packing assembly mounted on the mandrel; an anchoring assembly mounted on the mandrel; a retaining element mounted on the mandrel, and a wear resistant insert mounted on the outer surface of one of the retaining elements.
 2. The packer tool of claim 1 wherein the retaining element comprise a spacer ring and a muleshoe.
 3. The packer tool of claim 2 wherein a wear resistant insert is mounted on the outer surface of the muleshoe.
 4. The packer tool of claim 2 wherein a wear resistant insert is mounted on the outer surface of the spacer ring.
 5. The packer tool of claim 2 wherein a wear resistant insert is mounted on both the outer surface of the muleshoe and the spacer ring.
 6. The packer tool of claim 1 wherein the wear resistant insert comprises metallic-ceramic composite material.
 7. The packer tool of claim 1 wherein the wear resistant insert comprises a zirconia ceramic compound.
 8. The packer tool of claim 1 wherein the wear resistant insert comprises a drillable cast iron material.
 9. The packer tool of claim 1 wherein the wear resistant insert comprises a titanium compound having a density ranging between about 5 to 7 grams per cubic centimeter.
 10. The packer tool of claim 1 wherein the retaining element containing a wear resistant insert comprises engineering grade plastic material.
 11. The packer tool of claim 1 wherein the wear resistant insert extends radially outward at least as far as the remaining portions of the tool.
 12. An improved packer tool for installation in the wellbore at a subterranean location, the plug having an upper end for being positioned in the wellbore closest to the wellhead and a lower end for being positioned furthest away from the wellhead, the plug comprising a tubular mandrel, a packing assembly comprising an annular member comprising deformable material, the annular member being of a size and shape such that when it is axially compressed it extends radially into contact with the wellbore, upper and lower opposed slip assemblies positioned on the mandrel, wherein the upper and lower slip assemblies each comprise an annular member with a wedge surface, an annular spacer ring and a plurality of slips located around the mandrel between an annular wedge surface and the annular shoulder of the slip support, the slips being of a size and shape that when the slip assemblies are axially compressed, the slips extend radially into contact with the wellbore, the packing assembly being positioned on the mandrel between the upper and lower opposed slip assemblies, components of the plug forming the outer surfaces comprise engineering grade plastic and, wherein the improvement comprises a plurality of wear resistant inserts installed on an outer surface of the plug so as to minimize abrasion damage to the plug from contact with the wellbore.
 13. The packer tool of claim 12, wherein the wear resistant inserts are made of a metallic-ceramic composite material.
 14. The packer tool of claim 12, comprising a muleshoe mounted on the mandrel and wherein wear resistant inserts are disposed in the muleshoe.
 15. The packer tool of claim 12, wherein wear resistant inserts are disposed in the outer surface of the spacer ring.
 16. The packer plug of claim 12, wherein at least one of plurality of wear resistant inserts is disposed in a surface of the plug with the largest outside diameter.
 17. The packer tool of claim 12, wherein the wear resistant inserts comprise metallic-ceramic composite material.
 18. The packer tool of claim 12, wherein the wear resistant insert comprises a zirconia ceramic compound.
 19. The packer tool of claim 12, wherein the wear resistant insert comprises a drillable cast iron material.
 20. The packer tool of claim 12 wherein the wear resistant inserts comprise a titanium compound having a density ranging between about 5 to 7 grams per cubic centimeter.
 21. The packer tool of claim 1 wherein the wear resistant inserts extend radially outward at least as far as the remaining portions of the tool. 